A reactor is one type of circuit component that performs a voltage step-up operation or step-down operation. JP 2012-248904A discloses, as a reactor for an on-board converter, a reactor that includes: a coil that includes a pair of winding portions that are formed by spirally winding a winding wire; a ring-shaped magnetic core that is provided inside and outside the winding portions; tubular bobbins that are interposed between the winding portions and the magnetic core; and a B-shaped frame bobbin.
The above-described magnetic core includes a plurality of core pieces and gap plates that are made of alumina or the like and are each interposed between core pieces that are adjacent to each other. Portions of the above-described magnetic core located inside the winding portions are stacked objects in which an intermediate core piece (corresponding to an inner core piece) and a gap plate are stacked one after the other and that are fixed using an adhesive. The above-described tubular bobbins are interposed between the inner circumferential surfaces of the winding portions and the stacked objects. The frame bobbin is interposed between end surfaces of the winding portions and end portion core pieces (corresponding to outer core pieces) that are located outside the winding portions, and is provided with a pair of through holes through which the stacked objects are respectively inserted. End surfaces of the intermediate core pieces exposed from the through holes and inner end surfaces of end portion core pieces are joined to each other using an adhesive. JP 2012-248904A discloses, for example, achieving mechanical protection using resin to cover a combined body that includes the above-described coil, the above-described magnetic core, the tubular bobbins, and the frame bobbin.